Local Area Networks (LANs) have been in existence for over 30 years. They are widely used in universities, enterprises and government offices. While LANs in the past have operated over wired media, lately we have been witnessing a boom in the deployment and usage of Wireless Local Area Networks (WLANs). Once only seen within large enterprises, WLANs are increasingly making their way into residential, commercial, industrial and public deployments. Recent efforts by telephone carriers to integrate LANs and WLANs into their wide-area service offerings are testimony to their growing role in the future of networking.
Voice continues to be the most predominant wireless application and in order to fully integrate with existing and future cellular systems both LANs and WLANs must deliver high quality voice service. In addition to voice services, carriers plan to offer other services such as video conferencing and data services such as Internet access.
FIG. 1 illustrates a typical wireless LAN environment. In a typical wireless LAN environment, data traffic such as Web browsing or FTP is predominantly in the downstream direction (i.e., from the Access Point 101 to the host 102 or 103) with only minimal data traffic in the upstream direction (i.e., from the host 102, 103 to the Access Point 101). Data transmission in the downstream typically predominates because users typically receive far more data than they send. However, data transmission in the upstream direction may include a user sending a large file via e-mail or via FTP to other users that are connected to the network. In theory, if the number of users sending large files in this way is large, the amount of data sent in the upstream direction may increase. However, typically, the amount of data sent in the upstream direction is much less than data sent in the downstream direction. As illustrated in FIG. 1, downstream data transmission is much greater than upstream data.
Voice transmission, on the other hand, is typically approximately the same in both downstream and upstream directions. However, because data transmission predominates over voice transmission in terms of bandwidth and most data transmission is in the downstream direction, the downstream data transmission may contend with and cause voice quality-of-service degradation. The downstream data transmission may not only interrupt downstream voice transmission at the access point locally but also may contend with the upstream voice transmission as well. Likewise, upstream data transmission, although typically less than downstream data transmission, may also interrupt upstream voice transmission locally at the host as well and contend with voice transmission in both directions. Finally, voice transmission may compete for resources from itself. For example, the upstream voice transmission may compete with downstream voice transmission.
Attempts have been made to resolve the problem of shared media taking quality of service into account. However, no satisfactory solution has been found to date. One method of dealing with the problem involves priority control of the shared media. In this method, a higher priority is assigned to voice transmission and a lower priority is assigned to data transmission. A separate queue is implemented in an access point for voice and for data with a higher priority assigned to the voice data queue. In this way, voice packets are transmitted over data packets if voice packets are in the queue. However, this priority control alone is not enough to avoid the effect of contention between distinct wireless nodes (access points and hosts) for shared wireless resources.
Currently, wireless LANs and most vendors do not provide satisfactory QoS function. With the prior art method, re-design of the access points and upgrading the hardware is necessary as well as changes in the access protocol for implementation. The IEEE 802.11 committee is working on the new standard for the access protocol to provide QoS over wireless LAN environment, which will also require hardware or firmware changes for implementation. This has proven to be problematic for users due to inconvenience and cost, for example.
Thus, a need exists in the art for better quality voice transmission, improved quality of service function (QoS) or better quality video or stream-based applications, for example, without changing the access protocol or the access point itself.